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• Fractionation of phytosterols and phytostanols by solvent system selection. • Solubility of phytosterols and -stanols in organic solutions with and without water. • Lower solubility of phytostanols when compared to phytosterols in studied systems. • Good correlation between experimental solubility data and studied models. • Crystallized product concentration trends estimated by the solubility data. Phytosterols (C 29 H 50 O), also known as plant sterols and stanols, are valuable biomolecules with a variety of applications in the pharma, food, and cosmetics industries. Phytosterols are typically manufactured from vegetable oil and tall oil feedstocks through a cooling crystallization process. Depending on the feedstock used, the composition regarding individual phytosterols and phytostanols (saturated analogs of phytosterols), also varies to a large extent. In the current research it was observed that by adding a small amount of water to the organic solvent [i.e., n(water)/n(acetone) of 0.17, n(water)/n(ethanol) of 0.13, and n(water)/n(ethyl acetate) of 0.10], the final phytosterol profile regarding phytosterol and phytostanol concentrations can be modified. This can be explained by the different solubility behavior of phytosterols and phytostanols in the studied solvent systems, based on experimental results obtained from transmissivity measurements. Phytostanols have surprisingly low solubility when compared to phytosterols in all the studied solvent systems. However, in the presence of water, phytosterol solubility decreased more compared to phytostanols. To the best of our knowledge, this is the first time that phytostanol solubility has been systematically studied. Moreover, phytosterol and phytostanol concentrations in a crystallized product with varying binary solvent systems containing water has not previously been reported. The measured experimental solubility data correlated well with the studied solubility models (van't Hoff, modified Apelblat, Buchowski-Ksiazaczak (λh), and polynomial equations). Understanding the solubility behavior of phytosterols and phytostanols allows to optimize the crystallization process itself toward a broader raw material selection, and better yield and quality in the production of phytosterols from plant-based raw materials. In addition, these findings can potentially be further utilized in phytosterol formulations for various applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The stirred-tank crystallizer (STC) is the widely used apparatus in industrial crystallization. However, it presents notable challenges, including a broad crystal size distribution (CSD) and fouling. Herein, the twisted hexagonal tube (THT) was employed for thiourea cooling crystallization. The THT exhibited superior heat transfer performance compared to the circular tube (CT) under identical conditions. Furthermore, the THT exhibited longer induction times and wider metastable zone width compared to STC and CT, indicating that the THT can effectively mitigate the nucleation rate. Crystals formed in the THT exhibited elliptical shapes, with a purity of 99.3 % and a target-product (425 μm) proportion of 78 wt%. Thiourea crystallized using the THT met the first-class in China standard HG/T 3454–2013, whereas those crystallized using STC and CT met the second-class standard. Consequently, the THT, as a novel tubular crystallizer, demonstrated considerable potential. [Display omitted] • Twisted hexagonal tube (THT) crystallizer was first time used for cooling crystallization. • THT has a higher heat-transfer efficiency in cooling crystallization compared with circular tube. • THT achieved highest target-product yield of 78 wt% with highest purity 99.3 %. [ABSTRACT FROM AUTHOR]

• A new method for transforming from a CLD to a PSD is proposed. • Image processing algorithms were used to construct the transformation method. • Crystallization kinetic parameters of L-carnitine acid were estimated and validated. • The accuracy of transforming CLD to PSD was verified by experiment. Crystallization kinetics and thermodynamics are fundamental in the development of crystallization processes. This work systematically measured the kinetic parameters during cooling crystallization in pure and mixed solvent systems of L-carnitine (LC) by the using of process analysis technologies (PATs). Chord length distribution (CLD) of crystals in the system was collected using Focused Beam Reflectance Measurement (FBRM) and was converted to crystal size distribution (CSD). A fast and simple converting method was established by combining the FBRM's working principle and image recognition techniques, considering both crystal orientation and non-spherical morphology. Further, the kinetic parameters were evaluated using an optimizing objective function merging changes in solution concentration and CSD. It reveals that LC crystal growth more likely follows size-independent growth mechanism. The accuracy of the kinetic parameter estimation was verified by comparing the experimental results to that obtained via process simulation using the estimated kinetic parameters under the same operating conditions. [ABSTRACT FROM AUTHOR]

The control of size distribution is important as it determines the efficiency of downstream processes. The crystalline particles with a narrow size distribution can be produced by controlling the time for the formation of the first crystal. In this study, we investigated the effects of aeration on desupersaturaion to improve size distribution during cooling process. The results show that aeration was able to induce nucleation even in the temperature range where spontaneous nucleation does not occur under certain cooling rate conditions. Furthermore, fine crystals with a narrow size distribution were obtained using aeration. The enhancement effect of desupersaturation was dependent on the aeration start temperature. Therefore, to improve the size and size distribution of crystals, it is important to determine the suitable aeration start temperature. In summary, the characteristics of crystalline particles obtained when aeration is performed could be evaluated based on the changes in the supersaturation of the solution. [Display omitted] • Aeration was introduced into cooling crystallization to improve size distribution. • Aeration allowed the production of fine crystals with a narrow size distribution. • The enhancement effect of desupersaturation depends on the aeration temperature. • A suitable aeration temperature is important to improve the characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • >82 % of Al can be transformed into soluble aluminum ammonium sulfate by ammonium sulfate roasting. • The transformed aluminum can be completely separated by water immersion without consuming inorganic acids. • Al can be recovered as ammonium aluminum sulfate from water leachate using cooling crystallization. • Al 2 O 3 with a purity of 99.15 % can be prepared from obtained ammonium aluminum sulfate after calcination. • Ammonium sulfate can be recycled, which not only reduces costs but also avoids environmental pollution. Secondary aluminum dross (SAD), a hazardous waste product generated during the recycling of aluminum-containing electrolytic waste and scrap aluminum products, contains a significant amount of valuable metal aluminum, soluble salts (such as sodium chloride and potassium chloride), and aluminum nitride. Because of its complex phases and chemical composition, approximately 95 % of SAD is disposed of by stockpiling on the spot, resulting in considerable ecological damage and threats to public health. This study proposes a sustainable and green process for selective separation and recovery aluminum oxide, which is a highly valuable material for SAD. The process primarily consists of ammonium sulfate roasting, water leaching, and cooling crystallization. First, ammonium sulfate roasting facilitates the transformation of aluminum into aluminum ammonium sulfate; by employing a roasting temperature of 425 ℃, m((NH 4) 2 SO 4): m(water-washed residue (WWR)) of 6:1, a roasting time of 90 min, a leaching temperature and time of 60 ℃ and 90 min, respectively, and a liquid to solid ratio of 8, over 82 % of Al was transformed into soluble aluminum ammonium sulfate, which is subsequently separated by water leaching. Next, Al was separated from impurities such as Fe, Ca, Si, and Mg in the water leachate using a cooling crystallization method. At the crystallization temperature of 0 ℃ and the crystallization time of 720 min, resulted in an aluminum ammonium sulfate recovery efficiency of 80.5 %. Subsequently, the crystals were calcined at 1200 ℃ for 240 min to obtain Al 2 O 3 with a purity of 99.15 % and an impurity metal content of less than 0.1 %. This process effectively reduces energy consumption, costs, chemical reagent usage, and environmental pollution, thus preventing potential environmental hazards and enhancing process economics. [ABSTRACT FROM AUTHOR]

Saline effluents containing primarily sodium chloride (NaCl) and sodium sulfate (Na2SO4) are generated from common salt production, tannery CETPs, textiles industries, desalination rejects, etc. In this work, experimental studies have been conducted for parametric evaluation of crystallization techniques for selective isolation of Na2SO4 and NaCl from saline effluent. Three crystallization approaches, i.e., evaporation-crystallization, cooling-crystallization, and antisolvent-crystallization, are assessed through parametric studies. A representative saline solution generated from a salt refinery unit is considered for the study. Lab-scale experiments were performed to determine the optimum process conditions for each crystallization process, and their performance was evaluated by estimating the separation efficiency. Chemical, P-XRD, and TGA analyses were performed to characterize the product composition, purity, and hydration state. For selective Na2SO4 recovery, cooling crystallization, and antisolvent crystallization were found suitable over evaporation crystallization. Subsequently, integrated process variants for cooling crystallization and antisolvent crystallization-based separation were developed. A techno-economic assessment (TEA) was performed to compare integrated process variants for the recovery of salts (Na2SO4 and NaCl) and establish the prospective towards commercialization. The parametric evaluation and TEA shows that the combined crystallization technologies can be potential approach to recover added-value products from saline effluents promoting waste to wealth notion. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper reports the solid-liquid phase equilibria of the CoSO 4 -H 2 O and CoSO 4 -H 2 SO 4 -H 2 O systems at low temperatures. Binary and ternary phase diagrams, including the stable solid phases CoSO 4 ·6H 2 O and CoSO 4 ·7H 2 O were established using experimental data and thermodynamic modeling applying the mixed-solvent electrolyte (MSE) model. The results showed that the addition of H 2 SO 4 shifts the eutectic temperature and concentration to lower values for cobalt sulfate and ice crystallization. The trends obtained from the experimental data and the modeling are consistent for the binary CoSO 4 -H 2 O system with good agreement, but the ternary CoSO 4 -H 2 SO 4 -H 2 O system shows some deviations. In general, the MSE model is shown to be reliable for inferring and establishing the phase diagram of the low-temperature system. The phase diagrams are helpful for designing the pathways of cooling crystallization and eutectic freeze crystallization and assessing the performance of the low-temperature crystallization process in the production of CoSO 4 hydrates. In addition, some practical examples of cooling crystallization and eutectic freeze crystallization of CoSO 4 solutions are provided. • Phase equilibria of the CoSO 4 -H 2 O and CoSO 4 -H 2 SO 4 -H 2 O systems at low temperatures • Cooling crystallization of cobalt sulphate hydrates • Eutectic freeze crystallization of cobalt sulphate heptahydrate [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of seeding temperature and the purity of seed crystals. • Optimum purity and solvent capacity of curcumin using the azeotrope of ethyl acetate/ethanol. • Recyclable positive azeotropes for reuse in the purification of curcumin. Purification of curcumin (CUR) from crude CUR, which is referred to as curcuminoids, has been conducted by cooling crystallization with the use of two azeotropes of ethyl acetate/ethanol (AZE-EA/EtOH) and ethyl acetate/isopropyl alcohol (AZE-EA/IPA), as compared to the use of single solvents, including acetone, EA, EtOH, and IPA. According to the determination of crude CUR solubility in those solvents, the effects of stirring, crystallization time, and seeding on the induction time, purity, and yield of CUR product were investigated on a small scale. Especially the effects of the purity of CUR seed crystals have a positive trend on the CUR purity. Seeding at a high temperature is suggested. The use of AZE-EA/EtOH shows the optimum purity of 94.0% and solvent capacity of 16.0 mg/mL with a yield of 29.0% by seeded cooling crystallization in a single step. Similar results are observed in the larger scale purification of CUR with a higher purity of 94.9%. After purification, the azeotropes can easily be recovered for reuse without changing their compositions, confirmed by GC, density, and boiling point determination. [ABSTRACT FROM AUTHOR]

1,2-Diphenylethane can be widely used in organic synthesis field because of its particular molecular structure. In order to gain high pure 1,2-diphenylethane, the mainly conventional purification method is vacuum distillation. However, the vacuum distillation exhausts excessive energy, needs heavy tower equipment, and it is not easy to achieve high pure product. To obtain high pure 1,2-diphenylethane, save money, and conserve energy, the cooling crystallization with ethanol is used to purify 1,2-diphenylethane. Firstly, the impact of crystallization temperature, crystal growing time, cooling rate, stirring speed, seed size, and seed weight on the cooling crystallization processes of 1,2-diphenylethane in ethanol were investigated. Then, the orthogonal experiment were also studied. It provides a reference for industrial cooling crystallization of 1,2-diphenylethane. [ABSTRACT FROM AUTHOR]

It was recently demonstrated that the technique of solid hollow fiber membrane-based cooling crystallization can be employed to achieve continuous polymer precipitation from a solution and subsequent polymer coating/encapsulation of sub-micrometer particles/drug crystals as well as nanoparticles in suspension. In this technique, there is no need for high pressure as in supercritical solvent-based anti-solvent crystallization; further, there is easy scale-up and production of free-flowing polymer-coated particles. There is a concern however, whether this crystallization method can be applied for an extended duration since the earlier studies were run for only about 10 min. In this work, the duration of the cooling crystallization-based coating process has been greatly extended from 10 min to 60 min and 120 min. Eudragit RL 100 was chosen as the coating polymer and Cosmo 55 (550 nm silica particles) was the host for the coating process in an acetone solution. Scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were employed to characterize the coated samples. The results showed that the solid hollow fiber membrane-based cooling crystallization performed successfully as a continuous crystallizer during extended time running operation. Characterization of the products by SEM and TGA indicated a stable product consistent with a uniform spherical shape. The coating thickness of the samples tended to be essentially identical for the extended-duration coating process as long as solvent loss by volatilization and uneven distribution of host particles in the feed solution-suspension was kept to a minimum. Unlabelled Image • Continuous polymer coating of suspended submicron silica particles was demonstrated. • The technique uses solid hollow fiber membrane-based cooling crystallizer. • Coating thickness on silica particles was uniform over a 60 min-long operation. • 550 nm silica particles were coated with ~31.5 nm polymer coating of Eudragit RL100. • There was no evidence of fouling of hollow fiber lumen vis-à-vis coating process. [ABSTRACT FROM AUTHOR]

CH 3 NH 3 SnI 3 crystals with largest size up to 10 mm × 6 mm × 6 mm were grown in aerobic environment using cooling crystallization method. XRD analysis of the crystal powder shows that the CH 3 NH 3 SnI 3 crystal grown is of cubic phase with lattice constants a = b = c = 6.2480 Å. XRD and EDX results show that the chemical properties of CH 3 NH 3 SnI 3 crystal are unstable in air, and the oxidation mechanism of CH 3 NH 3 SnI 3 was analyzed. HRTEM shows that the CH 3 NH 3 SnI 3 crystal grown is of good crystallinity. FT-IR spectrum of CH 3 NH 3 SnI 3 crystal was identified. The band gap E g of the CH 3 NH 3 SnI 3 crystal is estimated to be 1.33eV according to the absorption spectrum. First-principles calculation shows the band gap of cubic CH 3 NH 3 SnI 3 crystal is 1.36 eV, which is consistent with the experimental results. The thermal property of CH 3 NH 3 SnI 3 is analyzed by TG/DTG analysis. Our results show that CH 3 NH 3 SnI 3 crystal has potential application prospects in the field of solar cells, however its poor chemical stability in air, leading to the formation of SnI 4 and SnO would limit its application in photoelectric fields. • Large-sized MaSnI 3 crystals were obtained by a cooling crystallization method under aerobic environment. • XRD and EDS analysis show that MaSnI 3 is not stable in aerobic environment. • Band gap obtained by the first-principles calculation is 1.36 eV, which is similar to the experimental results (1.33 eV). [ABSTRACT FROM AUTHOR]

A crystallization scheme for the recovery and reuse of waste liquid after simultaneous desulfurization and denitrification by magnesium oxide/chlorine-based additive was proposed in this paper. Based on the constant-rate cooling crystallization method, the mechanisms of magnesium sulfate crystal formation and growth in the waste liquid were analyzed. Factors such as the solute mass fraction, stirring rate, cooling rate, and final cooling temperature were analyzed to understand their impact on crystal yield, composition, and morphology. The results indicated that supersaturation is the key factor in determining crystal size and form. All of the tested factors have a significant effect on the crystal form. As the initial concentration of solute increases and the final cooling temperature decreases, the spontaneous crystallization yield increases significantly. As the stirring rate and cooling rate increase, the spontaneous crystallization yield slightly decreases. [ABSTRACT FROM AUTHOR]

This work covers general multistage binary separations with application examples in cooling crystallization, evaporative crystallization and organic solvent nanofiltration. Deterministic global optimization is applied to identify optimal configurations of multistage separation networks and study their sensitivity to parameter values. Superstructure optimization is conducted for countercurrent cascades and also for general superstructures to identify new multistage configurations. Results show substantially reduced separation effort for alternative configurations in large parameter regions, specifically in regions where optimal countercurrent cascades have a low number of stages. General, simple design guidelines for multistage separation with a low number of stages are derived from rigorous global optimization by comparing results for different processes. [ABSTRACT FROM AUTHOR]

Spherical crystallization can be an important technological step in the production of a solid form active agent. By the production of spherical crystals, direct compression tablet making can be applied to the powder material. This method makes the tableting process quicker, shorter and more economical with reduced amounts of additives and a reduced number of technological steps. This way, the granulation method can be avoided, which is also advantageous for a moisture sensitive drug. In this paper, we presented Focused Beam Reflectance Measurement (FBRM) studies applied in the case of the non-typical spherical crystallization methods of the active pharmaceutical ingredient ambroxol hydrochloride. Spherical agglomeration and controlled cooling crystallization methods were carried out based on our previous studies regarding these methods and the crystal formation processes were investigated with FBRM probe. Critical agglomeration periods and other mechanisms, such as the breakage of the agglomerates and the precipitation of small particles, were investigated. Chord length values were observed continuously and samples were taken out in certain points of the crystallization. Particle size analysis was carried out in each case to obtain information on the particle size enlargement caused by the crystallization methods. With the application of light microscopic analysis, aspect ratio and roundness values were also determined to obtain pieces of information on the sphericity-changes of the particles throughout the crystallization and large improvements were presented either for these parameters (aspect ratio from ~ 1.7 to ~ 1.3; roundness from ~ 2.4 to ~ 1.5) and the mean particle size (from ~13 μm to 120–400 μm). Among others, it was revealed that after the spherical agglomeration method (SA), mostly crystal agglomerates were formed, while slow cooling crystallization with alternating temperature profile (ATP) yielded larger and probably harder individual crystals. [ABSTRACT FROM AUTHOR]

Power consumption in the field of evaporation and crystallization has attracted extensive attentions all over the world. In this paper, humidification and cooling crystallization methods are involved simultaneously to constitute a novel evaporation and crystallization configuration. In light of the thermal processes included, mathematical models based on the mass and energy equilibrium are established. The characteristics of the adopted evaporation and crystallization system (ECS) at the designed parameters are first simulated and analyzed, and the corresponding influence laws from the appointed key parameters are analyzed. Furthermore, a scale and economic analysis is also achieved to explore the application prospect of the evaporation crystallization system. The practicability of the novel evaporation and crystallization system at ambient temperature is verified, with a descent amplitude of 52.88% for the energy consumption of evaporated water within the prescribed range of the air mass flow rate. The simulation results indicate variation of the inlet air parameters, including the relative humidity and temperature, is not effective to improve the thermal efficiency of the evaporation and crystallization system, while an evident reduction for the energy consumption of evaporated water (ECEW) as 45.08 kWht −1 is achieved in response to the volume growth of the packings from 15 m 3 to 30 m 3 . Finally, it is also found that the cost of heat and mass transfer areas will rise significantly with the increase of the volume although the energy conversion is improved. [ABSTRACT FROM AUTHOR]

Combining cooling crystallization and antisolvent crystallization is advantageous as it not only enhances yield but also offers two manipulative variables to exercise greater control on the outcome of a crystallization process. This study investigates the combined cooling and antisolvent crystallization of l -asparagine monohydrate (LAM) from it's aqueous solution using isopropanol as antisolvent. Three well known cooling policies (cubic cooling, natural cooling, linear cooling) and three feeding policies that are inspired by these cooling policies are employed to investigate the effect of combined modes of operation on crystal yield and crystal size distribution (CSD). The resulting supersaturation profile for a combined mode is intuitive and can be construed by qualitative superposition of supersaturation profiles of individual modes. A significant enhancement in the yield has been observed in all combined modes compared to individual modes of crystallization. Similar to individual modes, the highest mean size was obtained by combining slow cooling and slow-antisolvent addition strategy. Further, a population balance model is developed for the combined cooling and antisolvent crystallization system and the model predicts the concentration and final CSD well for all the cases investigated. [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMW), produced during the olive oil extraction process, is a hardly degradable by-product characterized by significant high concentrations of organic compounds and complex mixtures of phenolic compounds. The treatment of OMW is considered as a very difficult task because phenolic content is highly problematic for aerobic or anaerobic treatment and at present there is no unique and affordable process for OMW treatment. On the other hand, phenolic compounds in OMW are considered as high added value constituents and their isolation, purification and recovery is related with the higher efficiency in the management and valorization of the olive mills effluents. Physicochemical treatment methods, based on membrane filtration suggested recently by several researchers, proved successful in the fractionation and isolation of phenolic compounds in the concentrated streams of either nanofiltration or reverse osmosis (RO) units. Unfortunately, rich in phenolics streams have a high content of monosaccharides or disaccharides since the molecular size of the sugars is comparable with the respective of individual phenolic compounds. The present work is associated with the development of a more sophisticated treatment process of wastewater through the application of membrane filtration, cooling crystallization and melt crystallization to enhance the isolation, recovery and purification of phenolic compounds when present at high concentrations. The experimental study was done in synthetic media simulating the RO concentrates of OMW. Glucose and most part of OMW polyphenols (including tyrosol, ferulic acid [FA] and trans-cinnamic acid [TCA]) served as model compounds for sugars and phenolic compounds, respectively. It was found that in the case of mixtures, high recovery yields of FA, tyrosol and TCA were achieved. [ABSTRACT FROM AUTHOR]

Potassium chloride crystals are cubic, which often leads to caking and greatly limits their applications. This caking can be overcome by modifying the crystal shape toward sphericity. Spherical particles have a high anti-caking ability and flowability. In this work, spherical KCl particles were prepared using a simple cooling crystallization process designed to function without additives. Among the four main processes in the crystallization of spherical particles, i.e., nucleation, growth, agglomeration, and attrition, agglomeration is the greatest contributor to the formation of spherical KCl particles, which were prepared following the principle that the adhesion force must be larger than the dispersion force. The adhesion free energy between KCl particles and solvents (i.e., water, n -hexane, formamide, diazomethane, methanol, ethanol, ethyl acetate, ethylene glycol, and dimethyl sulfoxide) was calculated using the Lifshitz–van der Waals acid–base approach, and water was found to be the most appropriate solvent because of its attractive interaction with the crystals. According to the relationship between the adhesion force and dispersion forces, we found that the stirring rate should be lower than 1300 rpm. Additionally, the effects of stirring rate and cooling rate on the KCl products were investigated and optimized, and the optimal conditions were found to be 400–500 rpm and 10–15 min/ ° C, respectively. All of the spherical KCl products prepared under the optimal conditions show a better morphology, flowability, and anti-caking performance than the original crystals. [ABSTRACT FROM AUTHOR]

The olive oil extraction process is of vital importance for the farmers at Mediterranean countries. However, olive oil production is directly associated with the co-production of large quantities of Olive Mill Wastewater (OMW), which are considered as wastes but at the same time can also be considered as byproducts enriched in high added value constituents, such as phenolic compounds. The idea in the present work is firstly to separate and isolate the low molecular size phenolic compounds from other organic compounds, of high molecular size, using a combination of membrane processes (Ultrafiltration, UF, Nanofiltration, NF, Reverse Osmosis, RO). Further exploitation of the RO concentrate with vacuum distillation and freeze drying leads to the recovery of solid mixtures of the phenolic compounds and sugars. The implementation of cooling crystallization as a next treatment process is suggested for the separation of the phenolic compounds from sugars based on their solubility differences as a function of temperature. Further isolation and purification of phenolic compounds, may be achieved using melting crystallization and each compound may be selectively crystallized at its respective freezing point. To test the purification system proposed here, model “synthetic solutions” were used. The model solutions were made up using compounds with different molecular sizes including phenolic compounds. In the present study, recovering and purification of phenolic compounds was examined by experiments in synthetic OMW, where sucrose and tyrosol were served as model compounds for sugars and phenolics respectively. [ABSTRACT FROM AUTHOR]

In chemical processing industries, crystallization is one of the most important operations to obtain solid products with desired purity and characteristics. With distinct processing problems for the conventional approaches for crystallization, research into alternate approaches such as ultrasound assisted crystallization has been on the forefront. The present work deals with comparison of the conventional approach and ultrasound assisted approach for crystallization of ammonium sulphate followed by detailed understanding into the effect of important operating parameters (initial concentration, pH, agitation speed, depth of horn, and cooling approach) on the metastable zone width and average crystal size. Ultrasound assisted crystallization has been investigated using both ultrasonic bath and ultrasonic horn to understand the effect of type of irradiation. It has been observed that the maximum reduction in the MSZW was obtained using ultrasonic horn under conditions of optimized initial concentration. The order of average crystal size obtained for ammonium sulphate was conventional cooling crystallization > ultrasonic bath > ultrasonic horn. The average crystal size obtained was in the range of 411–450 µm for conventional approach of cooling crystallization, 350–400 µm using ultrasonic bath and 200–250 µm using ultrasonic horn. The analysis of crystal size distribution and surface characteristics using the SEM analysis was also performed under set of optimized parameters established using the particle size analysis. Overall the work has clearly established that the ultrasound assisted crystallization gave better results as compared to the conventional cooling crystallization in terms of reduced metastable zone width, better crystal characteristics and less agglomeration. [ABSTRACT FROM AUTHOR]

In this work, pyrolysis oil produced by the slow pyrolysis of pinewood was the feed solution for a freeze concentration study and cooling crystallization recovery of levoglucosan. Liquid-liquid extraction of water-soluble compounds was performed by adding water to the original pyrolysis oil with ratios of 1:1 and 1:5 water: pyrolysis oil (wt%), respectively. A two-step suspension freeze concentration was then performed with the 1:1 and 1:5 aqueous pyrolysis oils (AqPO) to concentrate the solutions. The efficiency of water removal from AqPO was assessed by measuring the ice yield and distribution coefficient of ice impurities. Levoglucosan recovery from a supersaturated 1:1 AqPO-water mixture was performed for 37.5 min and 60 min by cooling crystallization with an aging time of 60 min. The average recovery rate of levoglucosan was 24 wt% with mean levoglucosan crystal size of 831 μm. [Display omitted] • Pyrolysis oil obtained from the slow pyrolysis of pinewood. • Freeze concentration of 1:1 and 1:5 aqueous pyrolysis oil extract (AqPO). • Levoglucosan recovery by cooling crystallization from 1:1 AqPO. [ABSTRACT FROM AUTHOR]

The paper proposes a model-based nonlinear model predictive control (NMPC) method for online control of crystal mean size and standard deviation in cooling crystallization process. Image analysis method using deep learning neural network and mathematical statistical method are performed to obtain the mean size and standard deviation of crystal population. The nonlinear prediction model for the NMPC is derived from the input and output data. The effectiveness of the proposed NMPC method is evaluated by the alum cooling crystallization experiments. Experimental results demonstrate the benefits of the proposed combination of image analysis and feedback control of the crystal mean size and standard deviation. The control performance of NMPC is superior to model-free path following control (PFC) method due to the prediction and optimization capabilities of NMPC. • Model-based nonlinear model predictive control for crystal mean size and standard deviation. • Model-free path following control for crystal mean size and standard deviation. • Image analysis method using deep learning to obtain pixel-level instance segmentation. • The effectiveness of the proposed control methods is evaluated by the alum cooling crystallization experiments. [ABSTRACT FROM AUTHOR]

The present work reports the comparison of the effectiveness of ultrasonic bath and horn for intensifying the cooling crystallization of oxalic acid for the first time. The effect of various parameters such as temperature, crystallization time, irradiation time, ultrasonic frequency and ultrasonic power on the crystal characteristics has been investigated. The average particle size of oxalic acid crystals reduced with an increase in irradiation time and ultrasonic power dissipation. Comparison of crystal characteristics obtained in ultrasonic bath with that obtained in the ultrasonic horn under optimized parameters revealed that the average size in the case of ultrasonic horn and bath were only marginally different. The studies related to the effect of different cooling modes using ultrasonic horn revealed that a narrow size distribution and lower average size of 357.2 µm was obtained for the cooling using ice cold water as compared to air cooling where observed mean size was 439.7 µm. A narrow particle size distribution was also obtained in the scale-up studies using ultrasound horn with mean size of 96.70 µm, which was significantly lower than 161.1 µm obtained under conventional approach. Overall significant process intensification benefits have been established for the ultrasound assisted approach for cooling crystallization of oxalic acid. [ABSTRACT FROM AUTHOR]

We apply the mass-count framework to understand and control batch cooling crystallization of paracetamol from ethanol. The aim is twofold: (1) to examine the crystallization/dissolution dynamics for this commonly studied system from the mass-count perspective and (2) to test the generality of the framework for establishing crystal size control. Toward the first aim, we gathered experimental results that reveal the dynamics of paracetamol crystallization and dissolution under different temperature profiles. In most situations, the observed dynamics align with expectations and can be interpreted as straightforward crystallization or dissolution. In some cases, however, the experimental results show dynamics that are complex and do not find clear mechanistic interpretation. Nevertheless, in gathering the experimental results we can characterize the dynamics directly in terms of the expected movement in MC space. Such a characterization is useful for establishing control. Toward the second aim, we employed the mass-count framework to develop feedback policies for controlling the mean crystal size. Here we find that, despite the noted complexities, the general control methodology is flexible. Experimental results confirm control over the mean crystal size for three test runs. [ABSTRACT FROM AUTHOR]

In the present study, the recovery of rare earth elements (REEs) from an apatite concentrate in the nitrophosphate process of fertilizer production has been studied. The apatite concentrate has been recovered from iron ore tailings in Sweden by flotation. In the first step, the apatite is digested in concentrated nitric acid, after which Ca(NO 3 ) 2 .4H 2 O is separated by cooling crystallization. The solution is then neutralized using ammonia whereby the REEs precipitate mainly as phosphates (REEPO 4 .nH 2 O) and together with calcium as REE n Ca m (PO 4 ) (3n + 2m) / 3 . In this work, the degree of rare earth coprecipitation during seeded cooling crystallization of Ca(NO 3 ) 2 .4H 2 O has been studied. The solubility of calcium nitrate tetrahydrate (Ca(NO 3 ) 2 .4H 2 O) in acidic nitrophosphoric acid solutions in the temperature range of − 2 °C to 20 °C has been determined. For the neutralization step, it is shown that the calcium concentration and the final pH play an important role in determining the concentration of REEs in the precipitate. It is found that reaching maximum recovery of REE with minimum simultaneous precipitation of calcium requires careful control of the final pH to about 1.8. It is further observed that the precipitation yield of REEs and iron is favored by a longer residence time and higher temperature. Finally, the effect of seeding with synthesized REE phosphate crystals as well as a mixture of REE and Ca phosphates on the precipitation rate and the composition of the precipitate was studied. [ABSTRACT FROM AUTHOR]

This work studies the use of pulsed ultrasound during cooling crystallization of paracetamol. The effect of the pulse time on the nucleation temperature, crystal size and shape was evaluated and compared to silent conditions and continuous sonication. Most work is performed in a batch crystallizer, though some preliminary data in a recirculation configuration is also provided. In both setups, the nucleation temperature increased by at least 8 °C when ultrasound was applied compared to the non-sonicated case. When ultrasound is switched on more than 10% of the time, a similar nucleation temperature as with continuous treatment is obtained. At this minimal pulse setting, a bubble population, consisting of both oscillating and dissolving bubbles, is present in the vessel at all times. The pulse threshold can be validated using bubble dissolution calculations, and its existence leads to a vast reduction in ultrasonic energy consumption compared to continuous sonication. Finally, this work shows that the final particle size of paracetamol can be controlled in the batch setup by the pulse conditions, without affecting the crystal shape. The recirculation system shows a similar response, although further validation is recommended. [ABSTRACT FROM AUTHOR]

2D population balance model is presented for stirred cooling crystallizer of high aspect ratio crystals including primary and secondary nucleation, size-dependent growth of the two characteristic crystal facets and linear and nonlinear breakage along the crystal length. Three breakage mechanisms are modelled: crystal-impeller and crystal-wall collisions linear and crystal–crystal collisions nonlinear breakage processes. The 2D population balance equation is reduced into a system of moment equations for the mixed moments of length and width variables which is closed applying the quadrature method of moments and solved by using a three point QMOM-ODE method. It was shown that strong interactions exist between the secondary nucleation, crystal growth and breakage processes connected by the CSD. The stirring rate has strong impact on crystallization of high aspect ratio crystals forming the crystalline product directly by breakage. The crystal-impeller breakage proved to be the dominant process but the crystal–crystal breakage also play significant role. [ABSTRACT FROM AUTHOR]

In this paper calibration model building based on using an ATR-FTIR spectroscopy is investigated for in-situ measurement of the solution concentration during a cooling crystallization process. The cooling crystallization of L-glutamic Acid (LGA) as a case is studied here. It was found that using the metastable zone (MSZ) data for model calibration can guarantee the prediction accuracy for monitoring the operating window of cooling crystallization, compared to the usage of undersaturated zone (USZ) spectra for model building as traditionally practiced. Calibration experiments were made for LGA solution under different concentrations. Four candidate calibration models were established using different zone data for comparison, by using a multivariate partial least-squares (PLS) regression algorithm for the collected spectra together with the corresponding temperature values. Experiments under different process conditions including the changes of solution concentration and operating temperature were conducted. The results indicate that using the MSZ spectra for model calibration can give more accurate prediction of the solution concentration during the crystallization process, while maintaining accuracy in changing the operating temperature. The primary reason of prediction error was clarified as spectral nonlinearity for in-situ measurement between USZ and MSZ. In addition, an LGA cooling crystallization experiment was performed to verify the sensitivity of these calibration models for monitoring the crystal growth process. [ABSTRACT FROM AUTHOR]

Development and design of crystallization process strongly depend on accurate solid-liquid equilibrium data. In this paper, the solubility of 3-chlorophthalic anhydride and 4-chlorophthalic anhydride in methyl acetate + cyclohexane binary solvent mixtures was determined from T = (283.15 to 328.15) K by gravimetric method under atmospheric pressure. The results show that the solubility of 3-chlorophthalic anhydride and 4-chlorophthalic anhydride increases with the increasing of temperature at constant solvent composition. At fixed temperature, the solubility of 3-chlorophthalic anhydride increases with mole fraction of methyl acetate increasing. Nevertheless, the solubility of 4-chlorophthalic anhydride displays a maximum with the solvent composition changing. To extend the applicability range of the solubility data, experimental solubility data in binary solvent mixtures was correlated by the modified Apelblat equation, the CNIBS/R-K equation and the Jouyban-Acree equation. It is found that the correlated data is in good agreement with the experimental data. The metastable zone width (MSZW) of 3-chlorophthalic anhydride and 4-chlorophthalic anhydride were also determined by the polythermal method at three different cooling rates. Finally, the cooling crystallization process of 3-chlorophthalic anhydride was designed to separate and purify 3-chlorophthalic anhydride according to its solubility and MSZW data. [ABSTRACT FROM AUTHOR]

Olive Mill Wastewaters (OMW), produced from olive processing for the extraction of olive oil by units scattered in the Mediterranean countries, is a hardly degradable byproduct due to very high concentration of organic load of complex composition. Several treatment methods have been proposed for the efficient treatment of OMW, but because of the high operational cost, the application of these methods seems to be prohibitive, as olive mills are small family units and operate only 3–4 months per year. In the present work, the implementation of a combination of physicochemical treatment methods is proposed for the effective treatment of OMW. Initially, a membrane filtration process was used (ultrafiltration, nanofiltration, and reverse osmosis membranes) for the fractionation of OMW in concentrate and permeate streams. OMW was thus sufficiently treated and as a result the final permeate of the reverse osmosis was a pure water stream appropriate for irrigation purposes or for reuse in the OMW premises. The concentrated fraction from NF and RO membranes was further treated, to separate and isolate carbohydrates and the phenolic compounds, through the implementation of adsorption on specific resins. Alternatively, the enriched in phenolic content concentrated fractions could be investigated for the possibility of their selective recovery from the respective solution by cooling crystallization, applied directly to the concentrated fractions. During this process, it is possible to recover a number of components from their solutions according to the respective freezing points. Two Poly-Phenols (PP) contained in the OMW, namely trans-cinnamic acid (TCA) and ferulic acid (FA) were examined for the possibility of their selective extraction from their aqueous solutions by cooling crystallization, in order an operational model of the process to be developed. Initially, short cooling crystallization experiment cycles were done to test the effect of molecular diffusion and convection phenomena to the total PP recovery. Furthermore, crystallization of FA and TCA was followed during one cooling cycle as a function of time past the immersion of a cold surface in hot homogeneous solutions of the test compounds. It was estimated that in the case of mixtures, a total recovery of 66% FA and 50% TCA was achieved. The combination of membrane filtration and cooling crystallization may be quite promising for the development of more effective and integrated exploitation of OMW abiding to the zero waste targets. [ABSTRACT FROM PUBLISHER]

• Membrane-assisted seeding process were on-line monitored and analysed. • Appropriate membrane-involved operation route can effectively control seeding. • Membrane-assisted seeding is a promising method for high-quality crystallization. Effective seeding is crucial for the accurate control of cooling crystallization. Herein, the supercooled solution near the membrane interface underwent nucleation, and the membrane-assisted seeding (MAS) was performed for the nucleation and growth control of ammonium persulfate cooling crystallization. Process analytical technologies (PAT) were introduced to obtain on-line nucleation and growth information for the evaluation of the developed MAS process. Experimental comparisons between MAS and conventional seeding crystallization indicated that an appropriate MAS condition could provide a moderate seeding condition. By controlling two key operating parameters, the optimized membrane-involved temperature (18 °C) and duration (30 min), the terminal products possessed narrow crystal size distribution (mean size, 1181 μm; coefficient of variation, 0.162), desired morphology, and high purity (>99.0 wt%). Overall, the results have verified the feasibility of MAS to crystalize products with high quality. [ABSTRACT FROM AUTHOR]

Two-dimensional population balance model for continuous cooling crystallization of high aspect ratio crystals, including nucleation, size-dependent growth of the two characteristic crystal facets and binary breakage along the crystal length is developed and analysed. The population balance equation is solved numerically using the 2D quadrature method of moments. The behaviour of the crystallizer and the effects of kinetic and process parameters on the characteristics of the crystal size distribution are analysed by detailed numerical experimentation. The binary breakage is described by four breakage rate functions comparing their effects on the mean length and mean aspect ratio of crystals. The simulation results revealed several interesting phenomena caused by interactions of the nonlinear sub-processes playing a relevant role in formulation of high aspect ratio crystals. Interactions of nucleation and size-dependent breakage may induce decrease in production of crystals. Size-dependent crystal breakage, decreasing the mean length of crystals induces some increase in their mean width. [ABSTRACT FROM AUTHOR]

Many active pharmaceutical ingredients (APIs) are poorly soluble and therefore poorly bioavailable. Advances in crystal engineering have motivated research into the design of pharmaceutical co-crystals. This study examines the formation of agomelatine–citric acid co-crystal in a batch cooling crystallization. Three linear cooling profiles (10 °C, 20 °C and 30 °C/h) were applied for both unseeded and seeded crystallization and the effect of the seeding temperature on the final crystal size distribution was systematically investigated. A mathematical model of the crystallization process, consisting of the population and mass balance, was formulated and solved using the finite difference method. The growth and nucleation rate constants were evaluated iteratively by the comparison of measured and simulated crystal size distributions. The similarities and differences between classical single-component crystallization and co-crystallization were discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heat and mass balances in the cooling crystallization batch reactor. [•] Depiction of the super-cooling and concentration distribution at various times. [•] Determination of mass layer distance adjacent to the cooled surface. [•] Comparative presentation of the % total recovery for the respective poly-phenol. [Copyright &y& Elsevier]

Abstract: In the dairy industry, lactose crystallization during refining typically generates a large number of fines (<100μm), which greatly reduces the efficiency of downstream processes. To overcome this problem, a strategy to minimize fines production was developed. On lab scale units, lactose crystals were produced from three crystallizers (draft-tube baffled, anchor and paddle) operated with three cooling profiles (at different region inside metastable zone (MSZ)). Computational fluid dynamics was used to simulate the flow profile. Among all combinations investigated, anchor crystallizer (lowest shear) operated at slow cooling rate (in upper MSZ) produces the largest crystals with minimal fines. Then, the design strategy was applied in industrial scale crystallizer. The 13h cooling profile created for operation in the medium MSZ region successfully produced crystals with 28% less fines than the typical process. Therefore, depending on the crystallizer design and operational region (in MSZ), production of fines can be minimized. [Copyright &y& Elsevier]

• Ultrasound assisted crystallization of Azithromycin for control on particle size. • Understanding into effect of operating parameters and type of crystallization. • Characterization studies to analyse effect of ultrasound on structure and shape of azithromycin. • Ultrasound improves the particle characteristics especially in terms of mean size and shape. The primary motive of the current work is to achieve smaller mean particle size with narrow size distribution that can enhance the bioavailability of azithromycin (ARZ), an essential requirement due to its poor water solubility. Recrystallization of ARZ was evaluated using cooling as well as antisolvent crystallization approaches in the presence of ultrasonic irradiation with detailed study into effect of different parameters such as ultrasonic power, time and temperature. Ultrasound assisted antisolvent crystallization at low temperatures (<10℃) yielded best size reduction up to 80% with narrower distribution and also gave better yield of the product, that too within 5 min of sonication. With scale up considerations, recirculation mode of operation was also evaluated which offered promising results for the size reduction. Images captured using optical microscope and SEM revealed a nearly uniform rod/plate-shaped geometry. Increase in amorphous nature of ARZ was confirmed based on XRD analysis. FTIR analysis showed no significant changes in the functional groups when compared to the original sample. Overall, the work demonstrated an improved reprocessing approach based on the use of ultrasound with insights into effect of operating parameters and effect of ultrasound on various characteristics. [ABSTRACT FROM AUTHOR]

A quasi-steady state model is developed for the analysis of cyclically operated continuous cooling crystallization processes used in the recovery of hydrated salts from brines. When reliable correlations for the progressive deterioration of the clean heat transfer coefficients and for salt solubility under the prevailing industrial conditions are available, the model provides for a rational approach towards the optimization of the design and operation of cooling crystallizers. The numerical solution of the model equations enables the quantitative investigation of the effects of various design and operating variables such as brine feed flow rate, coolant flow rate, available heat transfer surface and total cycle time on crystals yield and fractional recovery, as well as the effects of constraints on the availability of refrigerated coolant on the overall system performance. The systematic application of the model is illustrated by considering a two stage crystallization train for Glauber salt recovery from lake brine using experimentally generated data on the evolution of the heat transfer coefficient and on Na2SO4 solubility in the lake brine. Extensive results illustrate the trade offs associated with alternative operating policies. [ABSTRACT FROM AUTHOR]

The control of polymorphs and crystal habit in the cooling crystallization from an acetonitrile/water mixed solvent for the purification of N²-(1(S)-ethoxycarbonyl-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine was investigated. The obtained crystals had three polymorphs (I form, II form and III form). The I form is a stable form having the lowest solubility and tends to have a low content of N²-(1(S)-carboxy-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine (carboxyl derivative). So, the selective crystallization of I form was advantageous in terms of the yield and quality. By adjusting the pH of the crystallization system to between 4.5 and 5.5, but not less than 4.5, that goal could be achieved. Besides the polymorphism, two kinds of crystal habit (prismatic form and granular form) were observed in every polymorph. The selective crystallization of granular form was advantageous from the viewpoint of removal of N²-(1(R)-ethoxycarbonyl-3-phenylpropyl)-N6-trifluoroacetyl-L-lysine (diastereomer). It could be achieved by carrying out the crystallization under action of vibration or ultrasonic wave. [ABSTRACT FROM AUTHOR]

Abstract: One of the key decisions in designing solution crystallization processes is the selection of solvents. In this paper, we present a computer-aided molecular design (CAMD) framework for the design and selection of solvents and/or anti-solvents for solution crystallization. The CAMD problem is formulated as a mixed integer nonlinear programming (MINLP) model. Although, the model allows any combination of performance objectives and property constraints, in the case studies, potential recovery was considered as the performance objective. The latter, needs to be maximized, while other solvent property requirements such as solubility, crystal morphology, flashpoint, toxicity, viscosity, normal boiling and melting point are posed as constraints. All the properties are estimated using group contribution methods. The MINLP model is then solved using a decomposition approach to obtain optimal solvent molecules. Solvent design and selection for two types of solution crystallization processes namely cooling crystallization and drowning out crystallization are presented. In the first case study, the design of single compound solvent for crystallization of ibuprofen, which is an important pharmaceutical compound, is addressed. One of the important issues namely, the effect of solvent on the shape of ibuprofen crystals is also considered in the MINLP model. The second case study is a mixture design problem where an optimal solvent/anti-solvent mixture is designed for crystallization of ibuprofen by the drowning out technique. For both case studies the performance of the solvents are verified qualitatively through SLE diagrams. [Copyright &y& Elsevier]

Abstract: In the past years we evaluated different strategies with the aim of eliminating completely from the beet sugar factory, the traditional calco-carbonic purification process taking into account the well-known problems related to the utilization of lime and the production of carbonation sludge. To complete the picture of the possible solutions to be adopted for the elimination of the traditional purification process, we tested and evaluated in laboratory and in pilot plants a new eco-friendly proposal. The results obtained, as well as the proposed flow-sheet and some economic evaluations, are presented and discussed. [Copyright &y& Elsevier]

Abstract: A stable PLS calibration for solute concentration measurement in batch cooling crystallization processes is presented. Two example cases are included: Sulfathiazole dissolved in five different mixtures of water and 1-propanol and C15 dissolved in toluene. The data to be used in calibration are validated using Multivariate Statistical Process Control (MSPC) and sensitivity analyses criteria. Two Orthogonal Signal Correction (OSC) filters are compared as preprocessing techniques to enhance the model performance. The inherent criteria for selecting the best performing model was RMSEV of the test set. Models are validated with two different external test sets. One measured in conditions similar to calibration set and another measured in conditions close to true crystallization measurement conditions. The latter one tests the flexibility of the model to be used in future predictions. Results show that careful data and model validation steps clearly improve the modeling procedure. OSC filtering clearly simplified the model and also enhanced the performance of the PLS model. The models have successfully been used in several crystallization experiments. [Copyright &y& Elsevier]

Usually, boric acid obtained from the high‑magnesium borate minerals by sulfuric acid leaching contains many impurities and shows relatively low yields. This happens due to Mg2+ and H 3 BO 3 in the leachates, which are challenging to separate effectively using H 2 SO 4 as a leaching agent. In this work, an innovative approach to solving the disturbance of Mg2+ on solution purification was proposed. It was found that more than 90% Mg2+ could be removed in the form of the MgSO 4 ·H 2 O crystalline phase with a hydrothermal process. The ratio of H 3 BO 3 to Mg2+ in the aqueous solution was significantly increased in primary separation. The amount of H 3 BO 3 carried in the crystalline phase was <0.6%, meaning that the loss of H 3 BO 3 was low. After removing Mg2+, the solution could be used to prepare boric acid by subsequent cooling crystallization. The results showed that the impurity content of Mg in the H 3 BO 3 crystal phase was <0.01%, with a satisfactory regulation of the growth morphology. In terms of microscopic properties, larger clusters of Mg2+ associated with SO 4 2− were present due to the precursors of crystallization. However, the increase of H 3 BO 3 content weakened the hydration of Mg2+, which was favorable for the precipitation of MgSO 4 ·H 2 O. Thus, the separation of MgSO 4 and H 3 BO 3 in the leachate was realized successfully, extending the applicability of raw materials during the H 2 SO 4 leaching process. [Display omitted] • Tackling bottlenecks in producing boric acid using high-magnesium borate minerals. • A large amount of magnesium sulfate was recovered. • Recycling of the solution became possible. • Microscopic particle distribution was given during the pre-nucleation period. • The high content of Mg2+ impurity in boric acid products was reduced. [ABSTRACT FROM AUTHOR]

Concentrated brines and bitterns rejected from various processes contain mineral salts of economic value. For example, sulphate-rich bittern generated at saltworks in the Rajasthan state of India exceeds 3 million tons annually and requires adequate treatment. Resource recovery from such unutilized by-products presents a sustainable waste management approach. This work presents the development and evaluation of a process for sodium-sulphate (Na 2 SO 4) recovery from sulphate-rich bitterns using an integrated process combining cooling crystallization, filtration, and drying as major unit operations. A parametric study has been conducted to investigate the effect of various operating parameters on product (anhydrous sodium-sulphate) yield and quality. Chemical analysis, TGA, P-XRD, and SEM-EDX techniques were used to characterize the product quality and purity. Based on the parametric studies, a sodium-sulphate production process was designed, and material & energy balance was established. The mass balance calculations have shown that 1 ton of anhydrous Na 2 SO 4 (~97 wt% purity) can be produced from 6.31 tons of bittern having a sulphate ion concentration of about 140.8 ± 6.94 g/l. Subsequently, the economic feasibility of a 5 ton/day anhydrous Na 2 SO 4 capacity plant has been evaluated using the cost and profitability analysis. The engineering-economic calculations suggest that the sodium-sulphate production from bittern can be economically favourable, achieving a payback period of 3.5 years. The optimized parameters and economics presented in this paper could significantly help implement an actual sodium-sulphate recovery unit using sulphate-rich bittern as feed. [Display omitted] • Techno-economic feasibility of sodium-sulphate production from bittern is evaluated. • The effect of different parameters on product yield and quality has been investigated. • One ton of anhydrous sodium-sulphate (97% purity) can be produced from six tons of bittern. • Sodium-sulphate recovery from sulphate-rich bittern can be economically favourable at higher plant capacity. [ABSTRACT FROM AUTHOR]

The solubility of 1,1-diamino-2,2-dinitroethylene (FOX-7) in three binary mixed solvents (DMSO+H 2 O, EtOH, ACE) at different temperatures from (293.15 to 333.15) K were determined by using a laser dynamic monitoring technique. The results showed that the solubility of FOX-7 in mixed solvent increases with increasing the temperature and DMSO content. The modified Apelblat equation, van't Hoff equation, CNIBS/R-K model and Jouyban-Acree model was adopted to correlate the experimental solubility data, and all of these models provided a satisfactory result in binary solvents. In addition, the thermodynamic properties of the solution of different binary mixed solvents, such as enthalpy, Gibbs energy and entropy can be calculated by the van't Hoff equation and the Gibbs equation. Solid-liquid surface tension and surface entropy factor of FOX-7 were estimated by using the experimental solubility data. The solubility of FOX-7 will provide essential support for the further research of crystallization and spheroidization of FOX-7. The morphology of products crystallized in the DMSO+EtOH mixed solvent (x DMSO = 0.7668) were uniform and regular, which were observed by electron microscopy. The particle size distribution of the products was characterized by the BT-2002 laser particle size analyzer. The results showed that the products particle size distribution was narrow and uniform. • The solubility data of FOX-7 was measured in three binary solvents. • The experimental values were correlated and calculated by four equations. • Gibbs energy, enthalpy, entropy, solid-liquid surface tension and surface entropy factor of FOX-7 were well calculated. • Obtained a kind of FOX-7 crystal having a relatively regular shape and a nearly spherical shape. [ABSTRACT FROM AUTHOR]